Wedge drives are used in tools in metalworking, e.g. in presses. These wedge drives are usually connected to the devices that perform a stamping or other deformation procedure. A conventional wedge drive has an upper guide part, which includes a slider element and a slider guide element, and a lower guide part, which includes a driver element or vice versa. On the slider guide element side, the wedge drives are moved by a drive unit that exerts a generally vertical pressing force. On the driver element side, wedge drives are fastened to a base plate in the tool or press, onto which plate the work piece to be machined is also placed, either directly or by means of a corresponding support device.
DE 26 40 318 B2 has disclosed a wedge drive for redirecting a vertical pressing force into a force acting at an angle thereto for the forming process. This wedge drive is composed of a drive wedge on which a vertical force of a corresponding work press acts and a slider wedge, which transmits the force in the horizontal direction. The driver wedge and the slider wedge travel either over a rounded cooperating region or in another embodiment, over a roller.
DE 24 39 217 A1 has disclosed a wedge press with a prism-shaped wedge guide in which the contact surfaces are roof-shaped or trough-shaped and the roof or trough extends over the entire pressure-absorbing width of the wedge.
DE 23 29 324 B2 has disclosed a wedge press with a device for preventing unwanted movements of the wedge, which is equipped with a prism-shaped wedge guide.
Usually, overhead suspension wedge drives used in the auto body industry are composed of a driver, a slider, and a slider receptacle. The top of the slider receptacle is acted on by a vertical force that pushes the slider receptacle downward. The driver is firmly anchored in the tool, so that when pressure is exerted on the slider receptacle, the slider anchored in the slider receptacle is pushed in a freely selectable direction other than the vertical working direction.
Overhead suspension wedge drives are used frequently. With this design, the slider is suspended in its guide so that it is able to move in the slider receptacle. The driver is rigidly supported in the lower part and predetermines the working direction of the slider. With the downward stroke of the press, the slider, whose spring suspension has bottomed out, comes to rest on the driver and is pushed by the slider receptacle, which continues to move, across the driver surface in the working direction.
The wedge drives known from this prior art have disadvantages: the sliders used often have only short service lives and due to their structural design, are subject to a large amount of wear and tear. They must therefore be replaced often, even after short operating times, because the wear on them makes it impossible to continue redirecting the vertical pressing forces in a precise fashion, resulting in unacceptable tolerances for metal machining.
DE 197 53 549 C2 has disclosed a wedge drive that can be manufactured in a continuous industrial manufacturing process and should have a long service life. To guide the slider in the slider receptacle, angle bars are provided, which are made of bronze and which have glide elements made of graphite mounted in the angle bar. To redirect a vertical pressing force, this wedge drive is generally equipped with a driver, a slider, and a slider receptacle; the driver has a prism-shaped guide and the travel path of the slider on the driver is shorter than the travel path of the slider on the slider receptacle and the ratio of the travel paths to each other is at least 1 to 1.5 and the angle α between the travel paths is 50° to 70°. With a slider of this kind, the driver element has a prism-shaped surface, with the flanks of the prism-shaped surface embodied to slope downward toward the outside. This wedge drive also has forced return brackets on two opposite sides in the respective grooves of the slider element and driver element. If a spring element for returning the slider element breaks, these forced return brackets ensure that the slider element returns to its starting position, thus preventing screw-mounted stamped elements from being torn out. The slider element is fastened to the slider guide element by means of the angle bars and mounting screws and can be moved along the angle bars relative to the slider guide element.
U.S. Pat. No. 5,101,705 has disclosed another wedge drive in which the slider element is suspended on angle bars and is attached to the slider guide element by means of them. In this case, the plates that rest against each other and the elements required for fastening must be precisely ground to guarantee the required running clearance between the slider element and slider guide element. In this wedge drive and also the other known wedge drives in which the slider guide element and slider element are connected to each other by means of angle bars and screws, it is disadvantageous that all tensile forces are introduced into the screws, which particularly at the moment that an expansion of the screws and material surrounding them occurs, negatively affects the running clearance of the slider guide elements and slider elements, which move relative to each other. This then results in a reduced rigidity because there is a significant increase in wear due to the distortion of the tool in this region. In addition, it turns out to be disadvantageous that the slider element cannot expand laterally when heated since it is constricted in this respect by the angle bars. This can also lead to an increased wear on the tool.
EP 1 197 319 has disclosed a wedge drive in which the slider element and slider guide element are held together by means of guide brackets. This should render it unnecessary for additional angle bars or other devices connecting the two elements to be precisely ground in order to guarantee a required running clearance. Also, there is no adverse effect on the running clearance even with heating of the wedge drive and tool, because the connection by means of a guide bracket is able to absorb not only resulting expansions of the material but also production tolerances. There is thus also no longer any adverse effect on or reduction of the rigidity of the wedge drive. A high degree of running precision can be achieved despite the elimination of a grinding step. The guide brackets here engage with the slider guide element in a form-locked fashion; because of this form-locked engagement, the slider element is suspended on the slider guide element by means of the guide brackets. It is therefore not necessary for them to be secured to the slider guide element by means of screws that are on the one hand, susceptible to wear and on the other hand, can cause the above-mentioned adverse effect on the running clearance in the presence of heat.
The object of the invention is to create a wedge drive in which the amount of bronze material used is reduced, in which the force transfer region is optimized, and which has a more stable slider bed region.